Construction
Requirements Craft Wondrous Item, bull’s strength; Cost 500 gp
No Trace +4 (Ex) Survival DCs to track you are at +4, gain +4 to Disguise and Stealth when you are stationary and not acting.
Point Blank Shot +1 to attack and damage rolls with ranged weapons at up to 30 feet.
Poison Use You don't accidentally poison yourself with blades.
Precise Shot You don't get -4 to hit when shooting or throwing into combat.
Quick Draw Draw a weapon as a free action. Throw at full rate of attacks.
Rapid Shot You get an extra attack with ranged weapons. Each attack is at -2.
Sneak Attack +7d6 +7d6 damage if you flank your target or your target is flat-footed.
Swift as Shadows reduce the penalty for Stealth while moving by 5 and reduce the penalty for sniping by 10.
Vanishing Trick (Su) As a swift action, the ninja can disappear for 1 round per level. This ability functions as invisibility. Using this ability uses up 1 ki point.
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Muleback cords (150%, 1500gp) are in the Cloak of Resistance +4
Slippers of Spider Climbing (150% +2400gp) are in the Boots of Striding and Springing

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I would trade out iron will for TWF. Your damage will increase, and being invisible prevents you from being targeted by most spells that target will. I also don't see the need for the +1 Wakizashi. You may also want to replace clustered shots, the reason being is that your great variety of shurrikens covers most DR and stuff that isn't covered (like DR/good) can be replaced by a spell from someone else in the party.